RU2838192C1 - Aerosol-generating device, and system comprising induction heating device, and method for controlling thereof - Google Patents

Abstract

FIELD: smoking accessories.

SUBSTANCE: disclosed is a method of controlling aerosol production in aerosol-generating device (200) comprising an induction heating device (320) and power supply (310) for supplying power to the induction heating device (320). Method includes control of power supplied to device (320) for induction heating, to provide a step-by-step increase in temperature of current collector (160), associated with aerosol-generating device (200), from a first operating temperature to a second operating temperature, wherein current collector (160) is configured to heat aerosol-forming substrate (110), and wherein power is controlled based on measured resistance, conductivity or current associated with current collector, wherein the measured resistance, conductivity or current associated with the current collector is determined based on the direct current consumed from the power supply.

EFFECT: increased accuracy and reliability of temperature control and regulation of induction heating device.

25 cl, 8 dwg

Description

The present invention relates to an induction heating device for heating an aerosol-forming substrate. The present invention further relates to an aerosol-generating device comprising such an induction heating device and a method for controlling aerosol production in the aerosol-generating device.

Aerosol generating devices may comprise an electrically controlled heat source that is configured to heat an aerosol-forming substrate to produce an aerosol. The electrically controlled heat source may be an induction heating device. Induction heating devices typically comprise an inductor that is inductively coupled to a susceptor. The inductor generates an alternating magnetic field that causes heating in the susceptor. Typically, the susceptor is in direct contact with the aerosol-forming substrate and heat is transferred from the susceptor to the aerosol-forming substrate primarily by conduction. The temperature of the aerosol-forming substrate can be adjusted by adjusting the temperature of the susceptor. Therefore, for such aerosol generating devices, it is important to accurately monitor and adjust the temperature of the susceptor to ensure optimal aerosol generation and delivery to the user.

It would be desirable to provide temperature control and regulation of an induction heating device that is accurate, reliable and inexpensive.

According to an embodiment of the present invention, a method for regulating the production of an aerosol in an aerosol generating device is proposed. The device may comprise an induction heating device and a power source for supplying power to the induction heating device. The method may include regulating the power supplied to the induction heating device to ensure a stepwise increase in the temperature of a current collector associated with the aerosol generating device from a first operating temperature to a second operating temperature, wherein the current collector is configured to heat an aerosol forming substrate.

Regulating the power supplied to the induction heating device to provide a stepwise increase in the temperature of the susceptor allows for the generation of aerosol over a long period covering a full user session consisting of several puffs, such as 14 puffs, or a given time interval, such as 6 minutes, where the delivered substances (nicotine, flavors, aerosol volume, etc.) remain substantially constant for each puff throughout the user session. In particular, the stepwise increase in the temperature of the susceptor prevents a decrease in aerosol delivery due to depletion of the substrate near the susceptor and a decrease in thermal diffusion over time. In addition, the stepwise increase in temperature allows heat to spread within the substrate at each step.

The stepwise increase in the temperature of the current collector may include at least three successive temperature steps, each temperature step having a certain duration. During the duration of each temperature step, the temperature of the current collector may be maintained at a specified temperature. The duration may be at least 10 seconds. The duration may be from 30 seconds to 200 seconds. The duration may be from 40 seconds to 160 seconds. The first temperature step may have a longer duration than the subsequent temperature steps. The duration may be specified. The duration may correspond to a specified number of user puffs.

The stepwise increase of the current collector temperature may include more than two temperature steps and less than fourteen temperature steps. The stepwise increase of the current collector temperature may include more than two temperature steps and less than eight temperature steps.

The first operating temperature may be sufficient to produce an aerosol by the aerosol-forming substrate.

The method may further include determining a conductivity value or a resistance value associated with the current collector, wherein the power supplied to the induction heating device is controlled based on the determined conductivity value or the determined resistance value.

The induction heating device may comprise a DC to AC converter and an inductor connected to the DC to AC converter. The current collector may be configured to be inductively connected to the inductor.

Regulating the power supplied to the induction heating device may include interrupting the power supplied to the DC/AC converter when the determined conductivity value exceeds the preset conductivity threshold value and resuming the power supply to the DC/AC converter when the determined conductivity value is below the preset conductivity threshold value. Regulating the power supplied to the induction heating device may include interrupting the power supplied to the DC/AC converter when the determined resistance value is below the preset resistance threshold value and resuming the power supply to the DC/AC converter when the determined resistance value is above the preset conductivity threshold value.

Power from the power source may be continuously supplied to the inductor through a DC to AC converter. Power from the power source may be supplied to the inductor through a DC to AC converter in the form of a plurality of pulses, wherein each pulse is separated by a time interval. Regulating the power supplied to the induction heating device may include regulating the time interval between each of the plurality of pulses. Regulating the power supplied to the induction heating device may include regulating the duration of each pulse of the plurality of pulses.

The method may further include performing a calibration process for measuring one or more calibration values associated with the susceptor. Regulating the power supplied to the induction heating device may include regulating the power so that the temperature of the susceptor is regulated based on one or more calibration values.

One or more calibration values may comprise a first conductivity value associated with a first calibration temperature of the current collector, and a second conductivity value associated with a second calibration temperature of the current collector. Regulating the power supplied to the induction heating device may include maintaining the conductivity value associated with the current collector between the first conductivity value and the second conductivity value.

One or more calibration values may comprise a first resistance value associated with a first calibration temperature of the current collector, and a second resistance value associated with a second calibration temperature of the current collector. Regulating the power supplied to the induction heating device may include maintaining the resistance value associated with the current collector between the first resistance value and the second resistance value.

The current collector may comprise a first current-receiving material having a first Curie temperature and a second current-receiving material having a second Curie temperature. The second Curie temperature may be lower than the first Curie temperature. The second calibration temperature may correspond to the second Curie temperature of the second current-receiving material. The first and second current-receiving materials are preferably two separate materials that are connected together and, therefore, are in direct physical contact with each other, thereby ensuring that both current-receiving materials have the same temperature due to thermal conductivity. The two current-receiving materials are preferably two layers or strips that are connected along one of their main surfaces. The current collector may additionally comprise another additional third layer of current-receiving material. The third layer of current-receiving material is preferably made of the first current-receiving material. The thickness of the third layer of current-receiving material is preferably less than the thickness of the layer of the second current-receiving material.

Regulating the power supplied to the induction heating device may include regulating the power such that the temperature of the susceptor is between the first calibration temperature and the second calibration temperature.

The first operating temperature may be greater than or equal to the first calibration temperature. The second operating temperature may be less than or equal to the second calibration temperature.

The first calibration temperature may be from 150 degrees Celsius to 350 degrees Celsius, and the second calibration temperature may be from 200 degrees Celsius to 400 degrees Celsius. The temperature difference between the first calibration temperature and the second calibration temperature may be at least 50 degrees Celsius.

The calibration process may be performed while the user is operating the aerosol generating device to generate an aerosol.

Accordingly, the calibration values used to control the heating process are more accurate and reliable than if the calibration process were performed in production. This is especially important if the susceptor is part of a separate aerosol-generating product that is not part of the aerosol-generating device. In such circumstances, calibration in production is not possible.

The calibration process may be performed periodically based on one or more of: a specified time duration, a specified number of user puffs, a specified number of temperature steps, and a measured power source voltage.

Conditions may change during the user's use of the aerosol generating device. For example, the susceptor may move relative to the induction heating device, the power source (e.g., battery) may lose some efficiency over time, and so on. Accordingly, periodic calibration ensures the reliability of the calibration values, thereby ensuring that optimal temperature control is maintained throughout the use of the aerosol generating device.

Performing the calibration process may include the following steps: (i) adjusting the power supplied to the induction heating device to cause an increase in the temperature of the susceptor; (ii) monitoring at least a current value of the induction heating device; (iii) interrupting the power supply to the induction heating device when at least the current value reaches a maximum, wherein the current value at the maximum corresponds to a second calibration temperature of the susceptor; and (iv), when the current value associated with the susceptor reaches a minimum, adjusting the power supplied to the induction heating device to cause an increase in the temperature of the susceptor, wherein the current value at the minimum corresponds to a first calibration temperature of the susceptor. Monitoring at least a current value of the induction heating device may further include monitoring a voltage value of the induction heating device.

The method may further comprise repeating steps (i)-(iv) when the conductivity value associated with the current collector reaches a minimum. Upon completion of repeating steps (i)-(iv): the conductivity value corresponding to the current value at the maximum may be stored as a second calibration value, and the conductivity value corresponding to the current value at the minimum may be stored as a first calibration value. Alternatively, the resistance value corresponding to the current value at the maximum may be stored as a second calibration value, and the resistance value corresponding to the current value at the minimum may be stored as a first calibration value.

Performing the calibration process may include the following steps: (i) adjusting the power supplied to the induction heating device to cause an increase in the temperature of the susceptor; (ii) monitoring the conductivity value or the resistance value associated with the susceptor; (iii) interrupting the power supply to the induction heating device when the conductivity value reaches a maximum or when the resistance value reaches a minimum, wherein the maximum current value or the minimum resistance value corresponds to a second calibration temperature of the susceptor; and (iv), when the conductivity value reaches a minimum or the resistance value reaches a maximum, adjusting the power supplied to the induction heating device to cause an increase in the temperature of the susceptor, wherein the minimum conductivity value or the maximum resistance value corresponds to a first calibration temperature of the susceptor.

Steps (i)-(iv) may be repeated when the conductivity value reaches a minimum or the resistance value reaches a maximum.

Upon completion of repeating steps (i) to (iv), the maximum conductivity value or the minimum resistance value may be stored as the second conductivity value, and the minimum conductivity value or the maximum resistance value may be stored as the first conductivity value.

The calibration process is fast and reliable without delaying the formation of an aerosol. In addition, repeating the steps of the calibration process significantly improves the subsequent temperature control based on the calibration values obtained through the repeated calibration process, since the heat has had more time to distribute within the substrate. Carrying out the calibration process based on at least the measured current value assumes that the voltage of the power source remains constant. Thus, monitoring the conductivity value or the resistance value (and therefore using the measured values of both the current and the voltage) during the calibration process further increases the reliability of the calibration in the event of changes in the voltage of the power source over a long period of time (e.g. after repeated recharging).

The method may further comprise performing a preheating process to heat the current collector to a first calibration temperature. The preheating process may have a specified duration. The preheating process allows heat to spread in the substrate before the calibration process begins, thereby further increasing the reliability of the calibration values.

Performing the preheating process may include: regulating the power supplied to the induction heating device to cause an increase in the temperature of the susceptor; monitoring at least the current value of the induction heating device; and interrupting the power supply to the induction heating device when the current value reaches a minimum, wherein the current value at the minimum corresponds to the first calibration temperature of the susceptor.

If the current value reaches a minimum during the specified duration of the preheating process, the method may include interrupting the power supply to the induction heating device to cause a decrease in the temperature of the current collector and then resuming the power supply to the induction heating device to cause an increase in the temperature of the current collector to the first calibration temperature. Interrupting the power supply to the induction heating device and resuming the power supply to the induction heating device are repeated during the specified duration of the preheating process. The method may further include, if the current value of the current collector does not reach a minimum during the specified duration of the preheating process, stopping the operation of the aerosol generating device.

Performing the preheating process may include: adjusting the power supplied to the induction heating device to cause an increase in the temperature of the susceptor; monitoring the conductivity value or the resistance value associated with the susceptor; and interrupting the power supply to the induction heating device when the conductivity value reaches a minimum or when the resistance value reaches a maximum, wherein the conductivity value at the minimum or the resistance value at the maximum corresponds to the first calibration temperature of the susceptor.

If during the specified duration of the preheating process the conductivity value reaches a minimum or the resistance value reaches a maximum, the method may further include interrupting the power supply to the induction heating device to cause a decrease in the temperature of the current collector and then resuming the power supply to the induction heating device to cause an increase in the temperature of the current collector to the first calibration temperature. Interrupting the power supply to the induction heating device and resuming the power supply to the induction heating device may be repeated during the specified duration of the preheating process. If during the specified duration of the preheating process the conductivity value does not reach a minimum or the resistance value does not reach a maximum, the method may further include stopping the operation of the aerosol generating device.

Performing the preheating process steps for a specified duration allows heat to spread within the substrate in time to reach the minimum conductivity value measured during the calibration process, regardless of the physical state of the substrate (e.g. whether the substrate is dry or wet). This ensures the reliability of the calibration process.

Additionally, the current collector is preferably comprised in an aerosol-generating article that is designed to be inserted into an aerosol-generating device. Aerosol-generating articles that are not designed to be used with an aerosol-generating device will not exhibit the same behavior as authorized aerosol-generating articles. In particular, for aerosol-generating articles that are not designed to be used with an aerosol-generating device, the minimum current/conductivity value or the maximum resistance value will not be observed during the specified duration of the preheating process. Accordingly, this prevents the use of unauthorized aerosol-generating articles.

The method may further comprise measuring, at the input side of the DC/AC converter, the DC current drawn from the power source. The conductivity value or the resistance value associated with the current collector may be determined based on the DC supply voltage of the power source and based on the DC current drawn from the power source. The method may further comprise measuring, at the input side of the DC/AC converter, the DC supply voltage of the power source. This is due to the fact that there is a monotonic relationship between the actual conductivity (which cannot be determined if the current collector is part of the article) of the current collector and the conditional conductivity determined in this way (since the current collector will impart conductivity to the LCR (DC/AC converter) circuit to which it will be connected, since most of the load (R) will be due to the resistance of the current collector. The conductivity is equal to 1/R. Therefore, when reference is made in this text to the conductivity of the current collector, it is actually the conditional conductivity that is meant if the current collector is part of a separate aerosol generating article.

The first operating temperature may be from 150 degrees Celsius to 330 degrees Celsius, and the second operating temperature may be from 200 degrees Celsius to 400 degrees Celsius. The temperature difference between the first operating temperature and the second operating temperature may be at least 30 degrees Celsius.

The stepwise increase in the temperature of the current collector may include: a first temperature step having a temperature corresponding to the first operating temperature, wherein the first operating temperature is 330 degrees Celsius, a second temperature step having a temperature of 340 degrees Celsius, a third temperature step having a temperature of 345 degrees Celsius, a fourth temperature step having a temperature of 355 degrees Celsius, and a fifth temperature step having a temperature corresponding to the second operating temperature, wherein the second operating temperature is 380 degrees Celsius.

The current collector and the aerosol-forming substrate may form part of an aerosol-generating article, and the aerosol-generating device may be designed to be removably positioned in the aerosol-generating article.

According to another embodiment of the present invention, an aerosol generating device is proposed, comprising: a power source for supplying a DC supply voltage and a DC current, and an electronic circuit of the power supply unit connected to the power source. The electronic circuit of the power supply unit comprises: a DC to AC converter; an inductor connected to the DC to AC converter for generating an alternating magnetic field when excited by an alternating current from the DC to AC converter, wherein the inductor is configured to be connected to a current collector, wherein the current collector is configured to heat an aerosol-forming substrate; and a controller configured to regulate the power supplied to the electronic circuit of the power supply unit in order to cause a stepwise increase in the temperature of the current collector from a first operating temperature to a second operating temperature.

The stepwise increase in the temperature of the current collector may include at least three successive temperature steps, wherein each temperature step has a certain duration. During the duration of each temperature step, the controller may be configured to regulate the power supplied to the electronic circuit of the power supply unit to maintain the temperature of the current collector at a given temperature. The duration may be at least 10 seconds. The duration may be from 30 seconds to 200 seconds. The duration may be from 40 seconds to 160 seconds. The first temperature step may have a longer duration than the subsequent temperature steps. The duration of each temperature step may be set. The duration may correspond to a given number of puffs by the user. The stepwise increase in the temperature of the current collector may include more than two temperature steps and less than fourteen temperature steps. The stepwise increase in the temperature of the current collector includes more than two temperature steps and less than eight temperature steps. The first operating temperature may be sufficient for the aerosol to be formed by the aerosol-forming substrate.

The controller may be configured to determine a conductivity value or a resistance value associated with the current collector. The controller may be configured to regulate the power supplied to the power supply electronic circuit based on the determined conductivity value or the determined resistance value.

The regulation of power supplied to the electronic circuit of the power supply may include interrupting the power supplied to the DC-AC converter when a determined conductance value exceeds a preset conductance threshold value and resuming the power supplied to the DC-AC converter when the determined conductance value is below the preset conductance threshold value.

The regulation of the power supplied to the induction heating device may include interrupting the power supplied to the DC/AC converter when a determined resistance value is below a preset threshold resistance value and resuming the power supplied to the DC/AC converter when the determined resistance value is above a preset threshold conductance value.

The electronic circuit of the power supply unit can be designed to continuously supply power from the power source to the inductor through a DC to AC converter.

The electronic circuit of the power supply unit may be configured to supply power from a power source to the inductor through a DC to AC converter in the form of a plurality of pulses, each pulse being separated by a time interval.

Regulating the power supplied to the electronic circuit of the power supply unit may include regulating the time interval between each of the plurality of pulses. Regulating the power supplied to the electronic circuit of the power supply unit may include regulating the duration of each pulse of the plurality of pulses.

The controller may be further configured to perform a calibration process for measuring one or more calibration values associated with the current collector.

Regulating the power supplied to the electronic circuit of the power supply may include regulating the power supply such that the temperature of the current collector is regulated based on one or more calibration values.

One or more calibration values may comprise a first conductivity value associated with a first calibration temperature of the current collector, and a second conductivity value associated with a second calibration temperature of the current collector. Regulating the power supplied to the electronic circuit of the power supply may include maintaining the conductivity value associated with the current collector between the first conductivity value and the second conductivity value.

One or more calibration values may comprise a first resistance value associated with a first calibration temperature of the current collector and a second resistance value associated with a second calibration temperature of the current collector.

Regulating the power supplied to the induction heating device may include maintaining a resistance value associated with the current collector between a first resistance value and a second resistance value.

The second calibration temperature of the current collector may correspond to the Curie temperature of the current collector material.

Regulating the power supplied to the electronic circuit of the power supply may include regulating the power supply such that the temperature of the current collector is between the first calibration temperature and the second calibration temperature.

The first operating temperature may be greater than or equal to the first calibration temperature. The second operating temperature may be less than or equal to the second calibration temperature.

The first calibration temperature may be from 150 degrees Celsius to 350 degrees Celsius, and the second calibration temperature may be from 200 degrees Celsius to 400 degrees Celsius. The temperature difference between the first calibration temperature and the second calibration temperature may be at least 50 degrees Celsius.

The calibration process may be performed while the user is operating the aerosol generating device to generate the aerosol. The calibration process may be performed periodically based on one or more of: a specified time duration, a specified number of user puffs, a specified number of temperature steps, and a measured power source voltage.

Performing the calibration process may include the following steps: (i) regulating the power supplied to the electronic circuit of the power supply to cause an increase in the temperature of the current collector; (ii) monitoring at least the current value of the electronic circuit of the power supply; (iii) interrupting the power supply to the electronic circuit of the power supply when the current value reaches a maximum, wherein the current value at the maximum corresponds to the second calibration temperature of the current collector; and (iv), when the current value reaches a minimum, regulating the power supplied to the electronic circuit of the power supply to cause an increase in the temperature of the current collector, wherein the current value at the minimum corresponds to the first calibration temperature. Monitoring at least the current value of the electronic circuit of the power supply may include monitoring the voltage value of the electronic circuit of the power supply.

Performing the calibration process may further include: repeating steps (i)-(iv) when the current value of the electronic circuit of the power supply unit reaches a minimum. The controller may further be designed so that, upon completion of repeating steps i)-iv): storing the conductivity value corresponding to the current value at the maximum as a second calibration value and storing the conductivity value corresponding to the current value at the minimum as a first calibration value, or storing the resistance value corresponding to the current value at the maximum as a second calibration value and storing the resistance value corresponding to the current value at the minimum as a first calibration value.

Performing the calibration process may include the following steps: (i) adjusting the power supplied to the induction heating device to cause an increase in the temperature of the susceptor; (ii) monitoring the conductivity value or the resistance value associated with the susceptor; (iii) interrupting the power supply to the induction heating device when the conductivity value reaches a maximum or when the resistance value reaches a minimum, wherein the maximum conductivity value or the minimum resistance value corresponds to a second calibration temperature of the susceptor; and (iv), when the conductivity value reaches a minimum or the resistance value reaches a maximum, adjusting the power supplied to the induction heating device to cause an increase in the temperature of the susceptor, wherein the minimum conductivity value or the maximum resistance value corresponds to a first calibration temperature of the susceptor.

Performing the calibration process may further include repeating steps i)-iv) when the conductivity value reaches a minimum or the resistance value reaches a maximum. Upon completion of repeating steps (i)-(iv), the controller may further be configured to store the conductivity value at the maximum as a second calibration value and to store the conductivity value at the minimum as a first calibration value. Upon completion of repeating steps (i)-(iv), the controller may further be configured to store the resistance value at the minimum as a second calibration value and to store the resistance value at the maximum as a first calibration value.

The controller may be further configured to perform a preheating process for heating the current collector to the first calibration temperature. The preheating process may have a specified duration. Performing the preheating process may include: regulating the power supplied to the electronic circuit of the power supply unit to cause an increase in the temperature of the current collector; monitoring at least the current value of the electronic circuit of the power supply unit; and interrupting the power supply to the electronic circuit of the power supply unit when the current value reaches a minimum, wherein the current value at the minimum corresponds to the first calibration temperature of the current collector.

Performing the preheating process may further include, if the current value reaches a minimum during the specified duration of the preheating process, interrupting the power supply to the power supply electronic circuit to cause a decrease in the temperature of the current collector and then resuming the power supply to the power supply electronic circuit to cause an increase in the temperature of the current collector to the first calibration temperature. Interrupting the power supply to the power supply electronic circuit and resuming the power supply to the power supply electronic circuit may be repeated during the specified duration of the preheating process.

The controller may be further configured to, if the current value of the current collector does not reach a minimum during a specified duration of the preheating process, generate a control signal to stop the operation of the aerosol generating device.

Performing the preheating process may include: adjusting the power supplied to the induction heating device to cause an increase in the temperature of the susceptor; monitoring the conductivity value or the resistance value associated with the susceptor; and interrupting the power supply to the induction heating device when the conductivity value reaches a minimum or when the resistance value reaches a maximum, wherein the current value at the minimum or the resistance value at the maximum corresponds to the first calibration temperature of the susceptor.

If during the predetermined duration of the preheating process the conductivity value reaches a minimum or the resistance value reaches a maximum, the power supply to the induction heating device may be interrupted to cause a decrease in the temperature of the susceptor and the subsequent power supply to the induction heating device may be resumed to cause an increase in the temperature of the susceptor to the first calibration temperature. The interruption of the power supply to the induction heating device and the resumption of the power supply to the induction heating device may be repeated during the predetermined duration of the preheating process.

If the conductivity value does not reach the minimum or the resistance value does not reach the maximum within the specified duration of the preheating process, the operation of the aerosol generating device may be stopped.

The aerosol generating device may further comprise a current sensor configured to measure, on the input side of the DC/AC converter, the DC current consumed from the power source. The conductivity value and the resistance value associated with the current collector may be determined based on the DC supply voltage of the power source and based on the DC current consumed from the power source. The aerosol generating device may further comprise a voltage sensor configured to measure, on the input side of the DC/AC converter, the DC supply voltage of the power source.

The first operating temperature may be from 150 degrees Celsius to 330 degrees Celsius, and the second operating temperature may be from 200 degrees Celsius to 400 degrees Celsius. The temperature difference between the first operating temperature and the second operating temperature may be at least 30 degrees Celsius.

The stepwise increase in the temperature of the current collector may include: a first temperature step having a temperature corresponding to the first operating temperature, wherein the first operating temperature is 330 degrees Celsius, a second temperature step having a temperature of 340 degrees Celsius, a third temperature step having a temperature of 345 degrees Celsius, a fourth temperature step having a temperature of 355 degrees Celsius, and a fifth temperature step having a temperature corresponding to the second operating temperature, wherein the second operating temperature is 380 degrees Celsius.

The electronic circuit of the power supply may additionally contain a matching circuit for matching the impedance of the inductor with the impedance of the current collector.

The aerosol generating device may further comprise a housing having a cavity configured to accommodate with the possibility of removing the aerosol generating article. The aerosol generating article may comprise a substrate forming the aerosol and a current collector.

According to another embodiment of the present invention, an aerosol generating system is proposed, comprising an aerosol generating device described above and an aerosol generating article. The aerosol generating article may comprise an aerosol forming substrate and a current collector.

The current collector may comprise a first current collector material and a second current collector material, wherein the first current collector material is located in physical contact with the second current collector material. The first current collector material may be one of aluminum, iron and stainless steel, and wherein the second current collector material is nickel or a nickel alloy. The first current collector material may have a first Curie temperature and the second current collector material may have a second Curie temperature. The second Curie temperature may be lower than the first Curie temperature. The second calibration temperature may correspond to the second Curie temperature of the second current collector material.

In the context of this document, the term "aerosol generating device" refers to a device that interacts with an aerosol-forming substrate to generate an aerosol. The aerosol generating device may interact with one or both of an aerosol generating article containing an aerosol-forming substrate and a cartridge containing an aerosol-forming substrate. In some examples, the aerosol generating device may heat the aerosol-forming substrate to facilitate the release of volatile compounds from the substrate. An electrically powered aerosol generating device may comprise an atomizer, such as an electrical heater, for heating the aerosol-forming substrate to form an aerosol.

In the context of this document, the term "aerosol-generating system" refers to the combination of an aerosol-generating device with an aerosol-generating substrate. When the aerosol-generating substrate forms part of an aerosol-generating article, the aerosol-generating system refers to the combination of the aerosol-generating device with the aerosol-generating article. In an aerosol-generating system, the aerosol-generating substrate and the aerosol-generating device interact to generate an aerosol.

In the context of this document, the term "aerosol-forming substrate" refers to a substrate capable of releasing volatile compounds that can form an aerosol. The volatile compounds may be released by heating or burning the aerosol-forming substrate. As an alternative to heating or burning, in some cases the volatile compounds may be released by a chemical reaction or by mechanical action, such as ultrasonication. The aerosol-forming substrate may be a solid or a liquid, or may contain both solid and liquid components. The aerosol-forming substrate may be part of an aerosol-generating article.

As used herein, the term "aerosol-generating article" refers to an article that contains an aerosol-forming substrate that can release volatile compounds that can form an aerosol. The aerosol-generating article may be disposable. An aerosol-generating article that contains an aerosol-forming substrate that contains tobacco may be referred to herein as a tobacco stick.

The aerosol-forming substrate may comprise nicotine. The aerosol-forming substrate may comprise tobacco, for example, it may comprise a tobacco-containing material comprising volatile tobacco aromatic compounds that are released from the aerosol-forming substrate upon heating. In preferred embodiments, the aerosol-forming substrate may comprise a homogenized tobacco material, for example, leaf tobacco. The aerosol-forming substrate may comprise both solid and liquid components. The aerosol-forming substrate may comprise a tobacco-containing material comprising volatile tobacco aromatic compounds that are released from the substrate upon heating. The aerosol-forming substrate may comprise a non-tobacco material. The aerosol-forming substrate may further comprise an aerosol-forming agent. Examples of suitable aerosol-forming agents are glycerol and propylene glycol.

For the purposes of this document, "aerosol cooling element" refers to a component of an aerosol-generating article that is located downstream of the aerosol-generating substrate such that, in use, the aerosol generated by volatile compounds released from the aerosol-generating substrate passes through the aerosol cooling element and is cooled by it prior to inhalation by the user. An aerosol cooling element has a large surface area but produces a low pressure drop. Filters and other mouthpieces that produce a high pressure drop, such as filters made from fiber bundles, are not considered aerosol cooling elements. Chambers and cavities in an aerosol-generating article are not considered aerosol cooling elements.

For the purposes of this document, the term "mouthpiece" refers to the portion of an aerosol-generating article, aerosol-generating device, or aerosol-generating system that is placed in the mouth of the user for direct inhalation of the aerosol.

In the context of this document, the term "current collector" refers to an element containing a material that is capable of converting magnetic field energy into heat. When the current collector is in an alternating magnetic field, the current collector heats up. The heating of the current collector may be the result of at least one of hysteresis losses and eddy currents induced in the current collector, depending on the electrical and magnetic properties of the current collector material.

In the context of this document, with respect to an aerosol-generating device, the terms "upstream" and "front" and "downstream" and "rear" are used to describe the relative positions of components or portions of components of an aerosol-generating device with respect to the direction in which air flows through the aerosol-generating device during use. The aerosol-generating devices of the present invention comprise a proximal end through which the aerosol exits the device during use. The proximal end of the aerosol-generating device may also be referred to as the mouthpiece end or the downstream end. The mouthpiece end is downstream of the distal end. The distal end of the aerosol-generating article may also be referred to as the upstream end. Components or portions of components of an aerosol generating device may be described as being upstream or downstream of one another based on their relative positions relative to the airflow path of the aerosol generating device.

In the context of this document, with respect to an aerosol-generating article, the terms "upstream" and "front" and "downstream" and "rear" are used to describe the relative positions of components or portions of components of an aerosol-generating article with respect to the direction in which air flows through the aerosol-generating article during use. The aerosol-generating article of the present invention comprises a proximal end through which the aerosol exits the article during use. The proximal end of the aerosol-generating article may also be referred to as the mouthpiece end or the downstream end. The mouthpiece end is downstream of the distal end. The distal end of the aerosol-generating article may also be referred to as the upstream end. Components or parts of components of an aerosol-generating article may be described as upstream or downstream relative to one another based on their relative positions between the near end of the aerosol-generating article and the far end of the aerosol-generating article. The front side of a component or part of a component of an aerosol-generating article is the part at the end closest to the upstream end of the aerosol-generating article. The back side of a component or part of a component of an aerosol-generating article is the part at the end closest to the downstream end of the aerosol-generating article.

In the context of this document, the term "inductive coupling" refers to the heating of the current collector when an alternating magnetic field passes through it. Heating may be caused by the generation of eddy currents in the current collector. Heating may be caused by magnetic hysteresis losses.

In the context of this document, the term "puff" means the action of the user drawing the aerosol into his or her body through the mouth or nose.

The present invention is defined in the claims. However, a non-exhaustive list of non-limiting examples is provided below. Any one or more of the features of these examples may be combined with any one or more features of another example, embodiment or aspect described herein.

Example Ex1: A method for regulating the production of an aerosol in an aerosol generating device, wherein the device comprises an induction heating device and a power source for supplying power to the induction heating device, and wherein the method includes: regulating the power supplied to the induction heating device to ensure a stepwise increase in the temperature of a current collector associated with the aerosol generating device from a first operating temperature to a second operating temperature, wherein the current collector is configured to heat an aerosol forming substrate.

Example Ex2: The method according to example Ex1, wherein the stepwise increase in the temperature of the current collector comprises at least three successive temperature steps, wherein each temperature step has a certain duration.

Example Ex3: The method according to example Ex2, wherein during the duration of each temperature step the temperature of the current collector is maintained at a given temperature.

Example Ex4: The method according to example Ex2 or Ex3, wherein the duration is at least 10 seconds.

Example Ex5: The method according to example Ex2 or Ex3, wherein the duration is from 30 to 200 seconds.

Example Ex6: The method according to any of examples Ex2 or Ex3, wherein the duration is from 40 seconds to 160 seconds.

Example Ex7: The method according to any of the examples Ex2-Ex6, wherein the duration of each temperature step is predetermined.

Example Ex8: The method according to example Ex2 or Ex3, wherein the duration corresponds to a predetermined number of puffs by the user.

Example Ex9: The method according to any of the examples Ex2-Ex8, wherein the first temperature step has a longer duration than the subsequent temperature steps.

Example Ex10: The method according to any of examples Ex1-Ex9, wherein the stepwise increase in the temperature of the current collector comprises more than two temperature steps and less than fourteen temperature steps.

Example Ex11: The method according to any of examples Ex1-Ex10, wherein the stepwise increase in the temperature of the current collector comprises more than two temperature steps and less than eight temperature steps.

Example Ex12: The method according to any of the examples Ex1-Ex11, wherein the first operating temperature is sufficient for the aerosol-forming substrate to form an aerosol.

Example Ex13: The method according to any of examples Ex1-Ex12, further comprising: determining a conductivity value or a resistance value associated with the current collector, wherein the power supplied to the induction heating device is controlled based on the determined conductivity value or the determined resistance value.

Example Ex14: The method according to example Ex13, in which the induction heating device comprises a DC to AC converter and an inductor connected to the DC to AC converter, and wherein the current collector is arranged to be inductively connected to the inductor.

Example Ex15: The method according to example Ex14, wherein regulating the power supplied to the induction heating device includes interrupting the power supplied to the DC/AC converter when the determined conductivity value exceeds a preset conductivity threshold value and resuming the power supply to the DC/AC converter when the determined conductivity value is below a preset conductivity threshold value, or wherein regulating the power supplied to the induction heating device includes interrupting the power supplied to the DC/AC converter when the determined resistance value is below a preset resistance threshold value and resuming the power supply to the DC/AC converter when the determined resistance value is above a preset conductivity threshold value.

Example Ex16: The method according to example Ex14 or Ex15, wherein power from the power source is continuously supplied to the inductor via a DC-to-AC converter.

Example Ex17: The method according to any of examples Ex14-Ex16, wherein power from the power source is supplied to the inductor through a DC to AC converter in the form of a plurality of pulses, each pulse being separated by a time interval.

Example Ex18: The method according to example Ex17, wherein adjusting the power supplied to the induction heating device includes adjusting the time interval between each of the plurality of pulses.

Example Ex19: The method according to example Ex17, wherein adjusting the power supplied to the induction heating device includes adjusting the duration of each pulse of the plurality of pulses.

Example Ex20: The method according to any of examples Ex1-Ex19, further comprising performing a calibration process for measuring one or more calibration values associated with the current collector.

Example Ex21: The method according to example Ex20, wherein adjusting the power supplied to the induction heating device comprises adjusting the power supply such that the temperature of the susceptor is adjusted based on one or more calibration values.

Example Ex22: The method according to example Ex20 or Ex21, wherein one or more calibration values comprise a first conductivity value associated with a first calibration temperature of the current collector, and a second conductivity value associated with a second calibration temperature of the current collector.

Example Ex23: The method according to example Ex22, wherein regulating the power supplied to the induction heating device includes maintaining a conductivity value associated with the current collector between a first conductivity value and a second conductivity value.

Example Ex24: The method according to example Ex20 or Ex21, wherein one or more calibration values comprise a first resistance value associated with a first calibration temperature of the current collector, and a second resistance value associated with a second calibration temperature of the current collector.

Example Ex25: The method according to example Ex24, wherein regulating the power supplied to the induction heating device includes maintaining a resistance value associated with the current collector between a first resistance value and a second resistance value.

Example Ex26: The method according to any of examples Ex22-Ex25, wherein the current collector comprises a first current collector material having a first Curie temperature and a second current collector material having a second Curie temperature, wherein the second Curie temperature is lower than the first Curie temperature, and wherein the second calibration temperature corresponds to the second Curie temperature of the second current collector material.

Example Ex27: The method according to any of examples Ex22-Ex26, wherein adjusting the power supplied to the induction heating device comprises adjusting the power supply such that the temperature of the susceptor is between the first calibration temperature and the second calibration temperature.

Example Ex28: The method according to any of examples Ex22-Ex27, wherein the first operating temperature is greater than or equal to the first calibration temperature and wherein the second operating temperature is less than or equal to the second calibration temperature.

Example Ex29: The method according to any of examples Ex22-Ex28, wherein the first calibration temperature is from 150 degrees Celsius to 350 degrees Celsius, and the second calibration temperature is from 200 degrees Celsius to 400 degrees Celsius, wherein the temperature difference between the first calibration temperature and the second calibration temperature is at least 50 degrees Celsius.

Example Ex30: The method according to any of examples Ex20-Ex29, wherein the calibration process is performed during operation of the user with the aerosol generating device to generate an aerosol.

Example Ex31: The method according to any of examples Ex20-Ex30, wherein the calibration process is performed periodically based on one or more of: a specified time duration, a specified number of user puffs, a specified number of temperature steps, and a measured power source voltage.

Example Ex32: The method according to any of examples Ex22 to Ex31, wherein performing the calibration process comprises the following steps: (i) adjusting the power supplied to the induction heating device to cause an increase in the temperature of the susceptor; (ii) monitoring at least a current value of the induction heating device; (iii) interrupting the power supply to the induction heating device when the current value reaches a maximum, wherein the current value at the maximum corresponds to a second calibration temperature of the susceptor; and (iv), when the current value associated with the susceptor reaches a minimum, adjusting the power supplied to the induction heating device to cause an increase in the temperature of the susceptor, wherein the current value at the minimum corresponds to a first calibration temperature of the susceptor.

Example Ex33: The method according to example Ex32, wherein monitoring at least the current value of the induction heating device further comprises monitoring the voltage value of the induction heating device.

Example Ex34: The method according to example Ex32 or Ex33, further comprising repeating steps (i) to (iv) when the current value reaches a minimum.

Example Ex35: The method according to example Ex34, further comprising, after completing the repetition of steps i) to iv): storing the conductivity value corresponding to the maximum current value as a second calibration value and storing the conductivity value corresponding to the minimum current value as a first calibration value, or storing the resistance value corresponding to the maximum current value as a second calibration value and storing the resistance value corresponding to the minimum current value as a first calibration value.

Example Ex36: The method according to any of examples Ex22 to Ex29, wherein performing the calibration process comprises the following steps: i) adjusting the power supplied to the induction heating device to cause an increase in the temperature of the susceptor; ii) monitoring the conductivity value or the resistance value associated with the susceptor; iii) interrupting the power supply to the induction heating device when the conductivity value reaches a maximum or when the resistance value reaches a minimum, wherein the maximum conductivity value or the minimum resistance value corresponds to a second calibration temperature of the susceptor; and iv) when the conductivity value reaches a minimum or the resistance value reaches a maximum, adjusting the power supplied to the induction heating device to cause an increase in the temperature of the susceptor, wherein the minimum conductivity value or the maximum resistance value corresponds to a first calibration temperature of the susceptor.

Example Ex37: The method according to example Ex36, further comprising repeating steps i) to iv) when the conductivity value reaches a minimum or the resistance value reaches a maximum.

Example Ex38: The method according to example Ex37, further comprising, after completing the repetition of steps (i) to (iv), storing the maximum conductivity value as a second conductivity value and storing the minimum conductivity value as a first calibration value, or storing the minimum resistance value as a second calibration value and storing the maximum resistance value as a first calibration value.

Example Ex39: The method according to any of the examples Ex22-Ex38, further comprising performing a preheating process for heating the current collector to a first calibration temperature, wherein the preheating process has a predetermined duration.

Example Ex40: The method according to example Ex39, wherein performing the preheating process comprises: regulating the power supplied to the induction heating device to cause an increase in the temperature of the susceptor; monitoring at least a current value associated with the susceptor; and interrupting the power supply to the induction heating device when the current value reaches a minimum, wherein the current value at the minimum corresponds to a first calibration temperature of the susceptor.

Example Ex41: The method according to example Ex40, further comprising, if the current value reaches a minimum during a predetermined duration of the preheating process, interrupting the supply of power to the induction heating device to cause a decrease in the temperature of the susceptor and subsequently resuming the supply of power to the induction heating device to cause an increase in the temperature of the susceptor to the first calibration temperature.

Example Ex42: The method according to example Ex41, in which the interruption of the power supply to the induction heating device and the resumption of the power supply to the induction heating device are repeated for a predetermined duration of the preheating process.

Example Ex43: The method according to example Ex40, further comprising: if the current value of the current collector does not reach a minimum during a given duration of the preheating process, stopping the operation of the aerosol generating device.

Example Ex44: The method according to example Ex39, wherein performing the preheating process comprises: regulating the power supplied to the induction heating device to cause an increase in the temperature of the susceptor; monitoring a conductivity value or a resistance value associated with the susceptor; and interrupting the power supply to the induction heating device when the conductivity value reaches a minimum or when the resistance value reaches a maximum, wherein the conductivity value at the minimum or the resistance value at the maximum corresponds to a first calibration temperature of the susceptor.

Example Ex45: The method according to example Ex44, further comprising, if during a predetermined duration of the preheating process the conductivity value reaches a minimum or the resistance value reaches a maximum, interrupting the supply of power to the induction heating device to cause a decrease in the temperature of the susceptor and subsequently resuming the supply of power to the induction heating device to cause an increase in the temperature of the susceptor to the first calibration temperature.

Example Ex46: The method according to example Ex45, in which the interruption of the power supply to the induction heating device and the resumption of the power supply to the induction heating device are repeated for a predetermined duration of the preheating process.

Example Ex47: The method according to example Ex44, further comprising: if during a given duration of the preheating process the conductivity value does not reach a minimum or the resistance value does not reach a maximum, stopping the operation of the aerosol generating device.

Example Ex48: The method according to any of the examples Ex14 to Ex47, further comprising measuring, at the input side of the DC/AC converter, the DC current consumed from the power source, wherein the conductivity value and the resistance value associated with the current collector are determined based on the DC supply voltage of the power source and based on the DC current consumed from the power source.

Example Ex49: The method according to example Ex48, further comprising measuring at the input side of the DC/AC converter the DC supply voltage of the power source.

Example Ex50: The method according to any of examples Ex1-Ex49, wherein the first operating temperature is from 150 degrees Celsius to 330 degrees Celsius, and the second operating temperature is from 200 degrees Celsius to 400 degrees Celsius, and wherein the temperature difference between the first operating temperature and the second operating temperature is at least 30 degrees Celsius.

Example Ex51: The method according to examples Ex1-Ex50, in which the stepwise increase in the temperature of the current collector includes: a first temperature step having a temperature corresponding to a first operating temperature, wherein the first operating temperature is 330 degrees Celsius, a second temperature step having a temperature of 340 degrees Celsius, a third temperature step having a temperature of 345 degrees Celsius, a fourth temperature step having a temperature of 355 degrees Celsius, and a fifth temperature step having a temperature corresponding to the second operating temperature, wherein the second operating temperature is 380 degrees Celsius.

Example Ex52: The method according to any of examples Ex1-Ex51, wherein the current collector and the aerosol-generating substrate form part of an aerosol-generating article, wherein the aerosol-generating device is configured to be removably positioned for the aerosol-generating article.

Example Ex53: An aerosol generating device comprising: a power source for supplying a DC supply voltage and a DC current; an electronic circuit of the power supply unit connected to the power source, wherein the electronic circuit of the power supply unit comprises: a DC to AC converter; an inductor connected to the DC to AC converter for generating an alternating magnetic field when excited by an alternating current from the DC to AC converter, wherein the inductor is configured to be connected to a current collector, wherein the current collector is configured to heat an aerosol-forming substrate; and a controller configured to regulate the power supplied to the electronic circuit of the power supply unit in order to cause a stepwise increase in the temperature of the current collector from a first operating temperature to a second operating temperature.

Example Ex54: An aerosol generating device according to example Ex53, in which the stepwise increase in the temperature of the current collector comprises at least three successive temperature steps, each temperature step having a certain duration.

Example Ex55: An aerosol generating device according to example Ex54, wherein during the duration of each temperature step the controller is configured to regulate the power supplied to the electronic circuit of the power supply unit to maintain the temperature of the current collector at a given temperature.

Example Ex56: An aerosol generating device according to example Ex54 or Ex55, wherein the duration is at least 10 seconds.

Example Ex57: An aerosol generating device according to example Ex54 or Ex55, wherein the duration is from 30 seconds to 200 seconds.

Example Ex58: An aerosol generating device according to example Ex54 or Ex55, wherein the duration is from 40 seconds to 160 seconds.

Example Ex59: An aerosol generating device according to example Ex54 or Ex55, wherein the duration corresponds to a predetermined number of puffs by the user.

Example Ex60: An aerosol generating device according to any of examples Ex54-Ex59, wherein the first temperature step has a longer duration than the subsequent temperature steps.

Example Ex61: An aerosol generating device according to any of examples Ex54-Ex58, wherein the duration is predetermined.

Example Ex62: An aerosol generating device according to any of examples Ex53-Ex61, wherein the stepwise increase in the temperature of the current collector comprises more than two temperature steps and less than fourteen temperature steps.

Example Ex63: An aerosol generating device according to any of examples Ex53 to Ex61, wherein the stepwise increase in temperature of the current collector comprises more than two temperature steps and less than eight temperature steps.

Example Ex64: An aerosol generating device according to any of examples Ex53-Ex63, wherein the first operating temperature is sufficient for the aerosol to be formed by the aerosol-forming substrate.

Example Ex65: An aerosol generating device according to any one of examples Ex53-Ex64, wherein the controller is configured to determine a conductivity value or a resistance value associated with the current collector and regulate the power supplied to the electronic circuit of the power supply unit based on the determined conductivity value or the determined resistance value.

Example Ex66: An aerosol generating device according to any one of examples Ex53 to Ex65, wherein regulating the power supplied to the power supply electronic circuit comprises interrupting the power supplied to the DC/AC converter when the determined conductivity value exceeds a preset conductivity threshold value and resuming the power supply to the DC/AC converter when the determined conductivity value is below a preset conductivity threshold value, or wherein regulating the power supplied to the power supply electronic circuit comprises interrupting the power supplied to the DC/AC converter when the determined resistance value is below a preset resistance threshold value and resuming the power supply to the DC/AC converter when the determined resistance value is above a preset conductivity threshold value.

Example Ex67: An aerosol generating device according to any of examples Ex53-Ex66, wherein the electronic circuit of the power supply unit is configured to continuously supply power from the power source to the inductor via a DC to AC converter.

Example Ex68: An aerosol generating device according to any of examples Ex53-Ex67, wherein the electronic circuit of the power supply unit is configured to supply power from the power source to the inductor via a DC to AC converter in the form of a plurality of pulses, wherein each pulse is separated by a time interval.

Example Ex69: An aerosol generating device according to example Ex68, wherein regulating the power supplied to the electronic circuit of the power supply unit includes regulating the time interval between each of the plurality of pulses.

Example Ex70: An aerosol generating device according to example Ex68, wherein regulating the power supplied to the electronic circuit of the power supply unit includes regulating the duration of each pulse of the plurality of pulses.

Example Ex71: An aerosol generating device according to any one of examples Ex53-Ex70, wherein the controller is further configured to perform a calibration process for measuring one or more calibration values associated with the current collector.

Example Ex72: An aerosol generating device according to example Ex71, wherein regulating the power supplied to the electronic circuit of the power supply unit comprises regulating the power supply such that the temperature of the current collector is regulated based on one or more calibration values.

Example: Ex73: An aerosol generating device according to example Ex71 or Ex72, wherein the one or more calibration values comprise a first conductivity value associated with a first calibration temperature of the current collector and a second conductivity value associated with a second calibration temperature of the current collector.

Example Ex74: An aerosol generating device according to example Ex71, wherein regulating the power supplied to the electronic circuit of the power supply unit includes maintaining a conductivity value associated with the current collector between a first conductivity value and a second conductivity value.

Example Ex75: An aerosol generating device according to example Ex71 or Ex72, wherein the one or more calibration values comprise a first resistance value associated with a first calibration temperature of the current collector and a second resistance value associated with a second calibration temperature of the current collector.

Example Ex76: An aerosol generating device according to example Ex75, wherein regulating the power supplied to the induction heating device includes maintaining a resistance value associated with the current collector between a first resistance value and a second resistance value.

Example Ex77: An aerosol generating device according to any one of examples Ex73-Ex76, wherein the second calibration temperature of the current collector corresponds to the Curie temperature of the current collector material.

Example Ex78. An aerosol generating device according to any of examples Ex73-Ex77, wherein regulating the power supplied to the electronic circuit of the power supply unit includes regulating the power supply so that the temperature of the current collector is between the first calibration temperature and the second calibration temperature.

Example Ex79: An aerosol generating device according to any of examples Ex73-Ex78, wherein the first operating temperature is greater than or equal to the first calibration temperature and wherein the second operating temperature is less than or equal to the second calibration temperature.

Example Ex80: An aerosol generating device according to any of examples Ex73-Ex79, wherein the first calibration temperature is from 150 degrees Celsius to 350 degrees Celsius, and the second calibration temperature is from 200 degrees Celsius to 400 degrees Celsius, wherein the temperature difference between the first calibration temperature and the second calibration temperature is at least 50 degrees Celsius.

Example Ex81: An aerosol generating device according to any one of examples Ex71-Ex80, wherein the calibration process is performed during operation of the aerosol generating device by the user to generate an aerosol.

Example Ex82: An aerosol generating device according to any of examples Ex71-Ex81, wherein the calibration process is performed periodically based on one or more of: a predetermined duration of time, a predetermined number of user puffs, a predetermined number of temperature steps, and a measured power source voltage.

Example Ex83: An aerosol generating device according to any one of examples Ex71 to Ex82, wherein performing the calibration process comprises the following steps: i) regulating the power supplied to the electronic circuit of the power supply to cause an increase in the temperature of the current collector; ii) monitoring at least a current value of the electronic circuit of the power supply; iii) interrupting the power supply to the electronic circuit of the power supply when at least the current value reaches a maximum, wherein the current value at the maximum corresponds to a second calibration temperature; and iv) when the current value of the electronic circuit of the power supply reaches a minimum, regulating the power supplied to the electronic circuit of the power supply to cause an increase in the temperature of the current collector, wherein the current value at the minimum corresponds to the first calibration temperature.

Example Ex84: An aerosol generating device according to example Ex83, wherein monitoring at least a current value of the electronic circuit of the power supply further comprises monitoring a voltage value of the electronic circuit of the power supply.

Example Ex85: An aerosol generating device according to example Ex83 or Ex84, wherein performing the calibration process further comprises repeating steps i) to iv) when at least the current value associated with the current collector reaches a minimum.

Example Ex86: An aerosol generating device according to example Ex85, wherein the controller is further designed to, upon completion of the repetition of steps i) to iv): store the conductivity value corresponding to the current value at maximum as a second calibration value and store the conductivity value corresponding to the current value at minimum as a first calibration value, or store the resistance value corresponding to the current value at maximum as a second calibration value and store the resistance value corresponding to the current value at minimum as a first calibration value.

Example Ex87: An aerosol generating device according to any one of examples Ex71 to Ex82, wherein performing the calibration process comprises the following steps: i) adjusting the power supplied to the induction heating device to cause an increase in the temperature of the susceptor; ii) monitoring a conductivity value or a resistance value associated with the susceptor; iii) interrupting the power supply to the induction heating device when the conductivity value reaches a maximum or when the resistance value reaches a minimum, wherein the maximum conductivity value or the minimum resistance value corresponds to a second calibration temperature of the susceptor; and iv) when the conductivity value reaches a minimum or the resistance value reaches a maximum, adjusting the power supplied to the induction heating device to cause an increase in the temperature of the susceptor, wherein the minimum conductivity value or the maximum resistance value corresponds to a first calibration temperature of the susceptor.

Example Ex88: An aerosol generating device according to example Ex87, wherein performing the calibration process further comprises repeating steps i) to iv) when the conductivity value reaches a minimum or the resistance value reaches a maximum.

Example Ex89: An aerosol generating device according to example Ex88, wherein the controller is further designed to, upon completion of the repetition of steps i) to iv), store the conductivity value at maximum or the resistance value at minimum as a second calibration value and store the conductivity value at minimum or the resistance value at maximum as a first calibration value.

Example Ex90: An aerosol generating device according to any one of examples Ex66-Ex78, wherein the controller is further configured to perform a preheating process for heating the current collector to a first calibration temperature, wherein the preheating process has a predetermined duration.

Example Ex91: An aerosol generating device according to example Ex90, wherein performing the preheating process comprises: regulating the power supplied to the electronic circuit of the power supply unit to cause an increase in the temperature of the current collector; monitoring at least a current value of the electronic circuit of the power supply unit; and interrupting the power supply to the electronic circuit of the power supply unit when at least the current value reaches a minimum, wherein the conductivity value at the minimum corresponds to a first calibration temperature of the current collector.

Example Ex92: An aerosol generating device according to example Ex91, wherein performing the preheating process further comprises, if at least the current value reaches a minimum during a predetermined duration of the preheating process, interrupting the power supply to the electronic circuit of the power supply unit to cause a decrease in the temperature of the current collector and subsequently resuming the power supply to the electronic circuit of the power supply unit to cause an increase in the temperature of the current collector to a first calibration temperature.

Example Ex93: An aerosol generating device according to claim 92, wherein the interruption of the power supply to the electronic circuit of the power supply unit and the resumption of the power supply to the electronic circuit of the power supply unit are repeated for a predetermined duration of the preheating process.

Example Ex94: An aerosol generating device according to any one of paragraphs 91-93, in which the controller is further configured to, if at least the current value of the current collector does not reach a minimum during a predetermined duration of the preheating process, generate a control signal for stopping the operation of the aerosol generating device.

Example Ex95: An aerosol generating device according to claim 90, wherein performing the preheating process comprises: regulating the power supplied to the induction heating device to cause an increase in the temperature of the susceptor; monitoring the conductivity value or the resistance value associated with the susceptor; and interrupting the power supply to the induction heating device when the conductivity value reaches a minimum or when the resistance value reaches a maximum, wherein the current value at the minimum or the resistance value at the maximum corresponds to the first calibration temperature of the susceptor.

Example Ex96: An aerosol generating device according to example Ex95, wherein performing the preheating process further comprises, if during a predetermined duration of the preheating process the conductivity value reaches a minimum or the resistance value reaches a maximum, interrupting the power supply to the induction heating device to cause a decrease in the temperature of the susceptor and subsequently resuming the power supply to the induction heating device to cause an increase in the temperature of the susceptor to a first calibration temperature.

Example Ex97: An aerosol generating device according to example Ex96, wherein the interruption of the power supply to the induction heating device and the resumption of the power supply to the induction heating device are repeated for a predetermined duration of the preheating process.

Example Ex98: An aerosol generating device according to example Ex95, wherein performing the preheating process further comprises: if, during a predetermined duration of the preheating process, the conductivity value does not reach a minimum or the resistance value does not reach a maximum, stopping the operation of the aerosol generating device.

Example Ex99: An aerosol generating device according to any one of examples Ex65 to Ex98, further comprising: a current sensor configured to measure, on the input side of the DC/AC converter, a DC current consumed from the power source, wherein the conductivity value and the resistance value associated with the current collector are determined based on the DC supply voltage of the power source and based on the DC current consumed from the power source.

Example Ex100: An aerosol generating device according to example Ex99, further comprising a voltage sensor configured to measure, at the input side of the DC/AC converter, the DC supply voltage of the power source.

Example Ex101: An aerosol generating device according to any of examples Ex53-Ex100, wherein the first operating temperature is from 150 degrees Celsius to 330 degrees Celsius, and the second operating temperature is from 200 degrees Celsius to 400 degrees Celsius, wherein the temperature difference between the first operating temperature and the second operating temperature is at least 30 degrees Celsius.

Example Ex102: An aerosol generating device according to any one of examples Ex53-Ex101, wherein the stepwise increase in the temperature of the current collector comprises: a first temperature stage having a temperature corresponding to a first operating temperature, wherein the first operating temperature is 330 degrees Celsius, a second temperature stage having a temperature of 340 degrees Celsius, a third temperature stage having a temperature of 345 degrees Celsius, a fourth temperature stage having a temperature of 355 degrees Celsius, and a fifth temperature stage having a temperature corresponding to the second operating temperature, wherein the second operating temperature is 380 degrees Celsius.

Example Ex103: An aerosol generating device according to any one of examples Ex53 to Ex102, wherein the electronic circuit of the power supply further comprises a matching circuit for matching the impedance of the inductor to the impedance of the current collector.

Example Ex104: An aerosol generating device according to any of examples Ex53-Ex103, further comprising a body having a cavity configured to removably accommodate an aerosol generating article, wherein the aerosol generating article comprises an aerosol generating substrate and a current collector.

Example Ex105: An aerosol generating system comprising an aerosol generating device according to any of examples Ex53-Ex104 and an aerosol generating article, wherein the aerosol generating article comprises an aerosol generating substrate and a current collector.

Example Ex106: An aerosol generating system according to example Ex105, wherein the current collector comprises a first current collecting material and a second current collecting material, wherein the first current collecting material is located in physical contact with the second current collecting material.

Example Ex107: An aerosol generating system according to example Ex106, wherein the first current-collecting material is one of aluminum, iron and stainless steel, and wherein the second current-collecting material is nickel or a nickel alloy.

Example Ex108: An aerosol generating system according to example Ex106 or Ex107, wherein the first current-receiving material has a first Curie temperature and the second current-receiving material has a second Curie temperature, wherein the second Curie temperature is lower than the first Curie temperature.

Example Ex109: An aerosol generating system according to example Ex108, wherein the second calibration temperature corresponds to the Curie temperature of the second current-collecting material.

The examples will now be further described with reference to figures, where:

Fig. 1 shows a schematic cross-sectional view of an aerosol generating article;

Fig. 2A is a schematic cross-sectional view of an aerosol generating device for use with the aerosol generating article illustrated in Fig. 1;

Fig. 2B is a schematic cross-sectional view of an aerosol generating device in engagement with the aerosol generating article illustrated in Fig. 1;

Fig. 3 is a schematic diagram showing the induction heating device of the aerosol generating device described in relation to Fig. 2;

Fig. 4 is a schematic diagram showing the electronic components of the induction heating device described in relation to Fig. 3;

Fig. 5 shows a schematic representation of the LC circuit inductor of the load of the induction heating device described in relation to Fig. 4;

Fig. 6 is a graph of direct current versus time illustrating remotely detectable current changes that occur when a current-collecting material undergoes a phase transition associated with its Curie point;

Fig. 7 shows the temperature profile of the current collector during operation of the aerosol generating device; and

Fig. 8 is a block diagram showing a method for controlling aerosol production in the aerosol generating device shown in Fig. 2.

In Fig. 1, an article 100 generating an aerosol is illustrated. The article 100 generating an aerosol comprises four coaxially aligned elements: an aerosol-forming substrate 110, a support element 120, an aerosol-cooling element 130, and a mouthpiece 140. Each of these four elements is a substantially cylindrical element, wherein each of them has a substantially equal diameter. These four elements are arranged in series and surrounded by an outer wrapper 150 to form a cylindrical rod. An elongated current collector 160 is located in the aerosol-forming substrate 110 in contact with the aerosol-forming substrate 110. The current collector 160 has a length that is approximately the same as the length of the aerosol-forming substrate 110 and is located along the central axis in the radial direction of the aerosol-forming substrate 110.

Current collector 160 comprises at least two different materials. Current collector 160 has the form of an elongated strip, preferably having a length of 12 mm and a width of 4 mm. Current collector 160 comprises at least two layers: a first layer of a first current-receiving material, located in physical contact with a second layer of a second current-receiving material. Each of the first current-receiving material and the second current-receiving material may have a Curie temperature. In this case, the Curie temperature of the second current-receiving material is lower than the Curie temperature of the first current-receiving material. The first material may not have a Curie temperature. The first current-receiving material may be aluminum, iron or stainless steel. The second current-receiving material may be nickel or a nickel alloy. Current collector 160 may be formed by electrolytic deposition of at least one section of the second current-receiving material on a strip of the first current-receiving material. The current collector may be formed by applying a strip of the second current collector material to a strip of the first current collector material.

The aerosol generating article 100 has a near or mouth end 170, which the user inserts into his mouth during use, and a far end 180, located at the opposite end of the aerosol generating article 100 relative to the mouth end 170. In the assembled state, the total length of the aerosol generating article 100 is preferably approximately 45 mm, and the diameter is approximately 7.2 mm.

In use, air is drawn by the user through the aerosol generating article 100 from the distal end 180 to the mouth end 170. The distal end 180 of the aerosol generating article 100 may also be described as the upstream end of the aerosol generating article 100, and the mouth end 170 of the aerosol generating article 100 may also be described as the downstream end of the aerosol generating article 100. The elements of the aerosol-generating article 100 located between the mouth end 170 and the distal end 180 may be described as being upstream of the mouth end 170 or, alternatively, downstream of the distal end 180. The aerosol-forming substrate 110 is located at the distal or upstream end 180 of the aerosol-generating article 100.

The support element 120 is located immediately downstream of the aerosol-forming substrate 110 and abuts against the aerosol-forming substrate 110. The support element 120 may be a hollow cellulose acetate tube. The support element 120 positions the aerosol-forming substrate 110 at the extreme distal end 180 of the aerosol-generating article 100. The support element 120 also acts as a separator for separating the aerosol-cooling element 130 of the aerosol-generating article 100 from the aerosol-forming substrate 110.

The aerosol cooling element 130 is located immediately downstream of the support element 120 and abuts against the support element 120. In use, volatiles released from the aerosol-forming substrate 110 pass along the aerosol cooling element 130 in the direction of the mouth end 170 of the aerosol-generating article 100. The volatiles can be cooled inside the aerosol cooling element 130 to form an aerosol that is inhaled by the user. The aerosol cooling element 130 can comprise a corrugated and assembled sheet of polylactic acid surrounded by a wrapper 190. The corrugated and assembled sheet of polylactic acid forms several longitudinal channels that extend along the length of the aerosol cooling element 130.

The mouthpiece 140 is located immediately downstream of the aerosol cooling element 130 and is adjacent to the aerosol cooling element 130. The mouthpiece 140 contains a traditional filter made of cellulose acetate fiber with low filtration efficiency.

To assemble the aerosol-generating article 100, the four elements 110, 120, 130 and 140 described above are aligned and tightly wrapped in an outer wrapper 150. The outer wrapper may be a regular cigarette paper. The current collector 160 may be introduced into the aerosol-forming substrate 110 during the process used to form the aerosol-forming substrate 110, before assembling several elements to form a rod.

The aerosol generating article 100 shown in Fig. 1 is intended to cooperate with an aerosol generating device, such as the aerosol generating device 200 shown in Fig. 2A, to produce an aerosol. The aerosol generating device 200 comprises a body 210 having a cavity 220 configured to accommodate the aerosol generating article 100. The aerosol generating device 200 further comprises an induction heating device 230 configured to heat the aerosol generating article 100 to produce an aerosol. Fig. 2B illustrates the aerosol generating device 200 when the aerosol generating article 100 is inserted into the cavity 220.

The induction heating device 230 is illustrated in the circuit diagram in Fig. 3. The induction heating device 230 comprises a DC power source 310 and a heating device 320 (also referred to as a power supply electronic circuit). The heating device comprises a controller 330, a DC-to-AC converter 340, a matching circuit 350 and an inductor 240.

The DC power source 310 is configured to supply DC power to the heating device 320. In particular, the DC power source 310 is configured to supply DC power voltage ( _VDC ) and DC current ( _IDC ) to the DC/AC converter 340. Preferably, the power source 310 is a battery, such as a lithium iron phosphate battery. Alternatively, the power source 310 may be another type of charge storage device, such as a capacitor. The power source 310 may require recharging. For example, the power source 310 may have a capacity sufficient to ensure the possibility of continuous aerosol generation for a period equal to approximately six minutes, or for a period multiple of six minutes. In another example, the power source 310 may have a capacity sufficient to ensure the possibility of performing a given number of puffs or individual activations of the heating device.

The DC/AC converter 340 is configured to supply the inductor 240 with high-frequency alternating current. In the context of this document, the term "high-frequency alternating current" means alternating current with a frequency of about 500 kilohertz to about 30 megahertz. The high-frequency alternating current may have a frequency of about 1 megahertz to about 30 megahertz, such as about 1 megahertz to about 10 megahertz or, for example, about 5 megahertz to about 8 megahertz.

Fig. 4 schematically shows the electrical components of the induction heating device 230, in particular the DC/AC converter 340. The DC/AC converter 340 preferably comprises a class E power amplifier. The class E power amplifier comprises a transistor switch 410 comprising a field-effect transistor 420, for example a metal-oxide-semiconductor field-effect transistor, a transistor switch power supply circuit, indicated by arrow 430, for supplying a switching signal (gate-source voltage) to the field-effect transistor 420, and an LC load circuit 440 comprising a shunt capacitor C1 and a series connection of a capacitor C2 and an inductor L2 corresponding to the inductor 240. In addition, a DC power supply 310 is shown, comprising an inductor L1, for supplying a DC supply voltage V _DC , with a DC current I _DC , drawn from the DC power supply 310, during operation. The ohmic resistance R, representing the total ohmic load 450, which is the sum of the ohmic resistance R of the inductor _coil L2 and the ohmic resistance R _{of the load} of the current collector 160, is shown in more detail in Fig. 5.

Although the DC-to-AC converter 340 is shown as comprising a class E power amplifier, it should be understood that the DC-to-AC converter 340 may use any suitable circuit that converts DC to AC. For example, the DC-to-AC converter 340 may comprise a class D power amplifier comprising two transistor switches. As another example, the DC-to-AC converter 340 may comprise a full-bridge inverting power amplifier with four switching transistors operating in pairs.

Returning to Fig. 3, the inductor 240 can receive alternating current from the DC-AC converter 340 through the matching circuit 350 for optimal adaptation to the load, but the matching circuit 350 is not critical. The matching circuit 350 can include a small matching transformer. The matching circuit 350 can improve the efficiency of power transfer between the DC-AC converter 340 and the inductor 240.

As shown in Fig. 2A, the inductor 240 is located near the distal portion 225 of the cavity 220 of the aerosol generating device 200. Accordingly, the high-frequency alternating current supplied to the inductor 240 during operation of the aerosol generating device 200 causes the inductor 240 to generate a high-frequency alternating magnetic field in the distal portion 225 of the aerosol generating device 200. The alternating magnetic field preferably has a frequency of 1 to 30 megahertz, preferably 2 to 10 megahertz, such as 5 to 7 megahertz. As can be seen in Fig. 2B, when the aerosol-generating article 100 is introduced into the cavity 200, the aerosol-forming substrate 110 of the aerosol-generating article 100 is located near the inductor 240, so that the susceptor 160 of the aerosol-generating article 100 is located within this alternating magnetic field. When the alternating magnetic field penetrates the susceptor 160, the alternating magnetic field causes the susceptor 160 to heat up. For example, eddy currents are generated in the susceptor 160, which heats up as a result. Additional heating is provided by magnetic hysteresis losses inside the susceptor 160. The heated susceptor 160 heats the aerosol-forming substrate 110 of the aerosol-generating article 100 to a sufficient temperature for the formation of an aerosol. The aerosol is drawn further downstream through the aerosol generating article 100 and inhaled by the user.

The controller 330 may be a microcontroller, preferably a programmable microcontroller. The controller 330 is programmed to regulate the supply of power from the DC source 310 to the induction heating device 320 in order to regulate the temperature of the current collector 160.

In Fig. 6 there is illustrated the relationship between the direct current I _DC drawn from the power source 310 and time as the temperature of the current collector 160 (indicated by the dotted line) increases. The direct current I _DC drawn from the power source 310 is measured at the input side of the DC/AC converter 340. For illustrative purposes, it can be assumed that the voltage V _DC of the power source 310 remains approximately constant. As the current collector 160 is inductively heated, the apparent resistance of the current collector 160 increases. This increase in resistance is observed as a decrease in the direct current I _DC drawn from the power source 310, which at a constant voltage decreases as the temperature of the current collector 160 increases. The high-frequency alternating magnetic field provided by the inductor 240 induces eddy currents in the immediate vicinity of the surface of the current collector, that is, an effect that is known as the skin effect. The resistance of the current collector 160 depends partly on the electrical resistance of the first current collector material, the resistivity of the second current collector material, and partly on the depth of the surface layer in each material accessible to the induced eddy currents, and the resistivity in turn depends on the temperature. As the second current collector material reaches its Curie temperature, it loses its magnetic properties. This causes an increase in the surface layer accessible to the eddy currents in the second current collector material, which causes a decrease in the apparent resistance of the current collector 160. The result is a temporary increase in the detectable direct current I _DC , as the depth of the layer of the second current collector material begins to increase, the resistance begins to fall. This is visible as a valley (local minimum) in Fig. 6. The current continues to increase until the maximum layer depth is reached, which coincides with the point at which the second current collector material has lost its spontaneous magnetic properties. This point is called the Curie temperature and is visible as a rise (local maximum) in Fig. 6. At this point, the second current collector material has undergone a phase transition from a ferromagnetic or ferrimagnetic state to a paramagnetic state. At this point, the current collector 160 is at a known temperature (the Curie temperature, which is an internal temperature that depends on the specific material). If the inductor 240 continues to generate an alternating magnetic field (i.e., power to the DC/AC converter 340 is not interrupted) after the Curie temperature is reached, the eddy currents generated in the current collector 160 will collide with the resistance of the current collector 160, causing Joule heating in the current collector 160 to continue, and thus the resistance will again increase (the resistance will have a polynomial dependence on temperature, which for most metallic current collector materials can be approximated by a third-degree polynomial dependence for our purposes), and the current will again begin to drop as long as the inductor 240 continues to supply power to the current collector 160.

Thus, as can be seen from Fig. 6, the apparent resistance of the current collector 160 (and, accordingly, the current I _DC consumed from the power source 310) can change together with the temperature of the current collector 160 in a strictly constant ratio in certain ranges of the temperature of the current collector 160. The strictly constant ratio makes it possible to uniquely determine the temperature of the current collector 160 based on the determination of the apparent resistance or apparent conductivity (1/R). This is due to the fact that each determined value of the apparent resistance is characteristic only of one single value of the temperature, therefore, there is no ambiguity in the ratio. The constant ratio of the temperature of the current collector 160 and the apparent resistance makes it possible to determine and regulate the temperature of the current collector 160 and, thus, to determine and regulate the temperature of the substrate 110 forming the aerosol. The apparent resistance of the current collector 160 can be remotely detected by monitoring at least the direct current I _DC drawn from the direct current power source 310.

At least the direct current I _DC consumed from the power source 310 is controlled by the controller 330. Preferably, both the direct current I _DC consumed from the power source 310 and the direct current supply voltage V _DC are controlled. The controller 330 regulates the supply of power supplied to the heating device 320 based on the conductivity value or the resistance value, where the conductivity is defined as the ratio of the direct current I _DC to the direct current supply voltage V _DC and the resistance is defined as the ratio of the direct current supply voltage V _DC to the direct current I _DC . The heating device 320 may comprise a current sensor (not shown) for measuring the direct current I _DC . The heating device may further comprise a voltage sensor (not shown) for measuring the direct current supply voltage V _DC . The current sensor and the voltage sensor are located on the input side of the DC to AC converter 340. Direct current I _DC and optionally direct current supply voltage V _DC are fed through feedback channels to controller 330 to regulate the further supply of alternating current P _AC to inductor 240.

The controller 330 may regulate the temperature of the current collector 160 by maintaining the measured conductivity value or the measured resistance value at a target value corresponding to the target operating temperature of the current collector 160. The controller 330 may use any suitable control loop to maintain the measured conductivity value or the measured resistance value at the target value, such as using a proportional-integral-derivative control loop.

In order to take advantage of the strictly unchanged relationship between the apparent resistance (or apparent conductivity) of the current collector 160 and the temperature of the current collector 160 during user control for producing an aerosol, the conductivity value or the resistance value associated with the current collector and measured on the input side of the DC/AC converter 340 is maintained between a first calibration value corresponding to a first calibration temperature and a second calibration value corresponding to a second calibration temperature. The second calibration temperature is the Curie temperature of the second current collector material (an increase in the current graph in Fig. 6). The first calibration temperature is a temperature greater than or equal to the temperature of the current collector, at which the layer thickness of the second current collector material begins to increase (which leads to a temporary decrease in resistance). Thus, the first calibration temperature is a temperature greater than or equal to the temperature at the maximum permeability of the second current collector material. The first calibration temperature is at least 50 degrees Celsius lower than the second calibration temperature. At least the second calibration value can be determined by calibrating the current collector 160, as will be described in more detail below. The first calibration value and the second calibration value can be stored as calibration values in the memory of the controller 330.

Since the conductivity (resistance) will have a polynomial dependence on temperature, the conductivity (resistance) will behave non-linearly as a function of temperature. However, the first and second calibration values are chosen such that this dependence can be approximated as linear between the first calibration value and the second calibration value, since the difference between the first and second calibration values is small, and the first and second calibration values are at the upper end of the operating temperature range. Therefore, to bring the temperature to the target operating temperature, the conductivity is adjusted according to the first calibration value and the second calibration value using linear equations. For example, if the first and second calibration values are conductivity values, the target conductivity value corresponding to the target operating temperature can be specified using:

Where is the difference between the first conductivity value and the second conductivity value, and represents a percentage .

The controller 330 can regulate the power supply to the heating device 320 by adjusting the duty cycle of the switching transistor 410 of the DC/AC converter 340. For example, when heating, the DC/AC converter 340 continuously generates an alternating current that heats the current collector 160, and at the same time, the DC supply voltage V _DC and the DC current I _DC can be measured preferably every millisecond for 100 milliseconds. If the conductivity is controlled by the controller 330, then when the conductivity reaches or exceeds the value corresponding to the target operating temperature, the duty cycle of the switching transistor 410 is reduced. If the resistance is controlled by the controller 330, then when the resistance reaches or falls below the value corresponding to the target operating temperature, the duty cycle of the switching transistor 410 is reduced. For example, the duty cycle of the switching transistor 410 can be reduced to approximately 9%. In other words, the switching transistor 410 can be switched into a mode in which it generates pulses only every 10 milliseconds for 1 millisecond. During this 1 millisecond, in the on state (conducting state) of the switching transistor 410, the values of the DC supply voltage V _DC and the DC current I _DC are measured, and the conductivity is determined. When the conductivity decreases (or the resistance increases), which indicates that the temperature of the current collector 160 is below the target operating temperature, a pulse train with the selected excitation frequency for the system is again applied to the gate of the transistor 410.

Power can be supplied by the controller 330 to the inductor 240 in the form of a series of successive pulses of electric current. In particular, power can be supplied to the inductor 240 by means of a series of pulses, each of which is separated by a time interval. A series of successive pulses can contain two or more heating pulses and one or more probing pulses between successive heating pulses. The heating pulses have such an intensity as to heat the current collector 160. The probing pulses are isolated power pulses having such an intensity as not to heat the current collector 160, but rather to receive feedback on the conductivity value or the resistance value, and then on the change (decrease) in the temperature of the current collector. The controller 330 can regulate the power supply by regulating the duration of the time interval between successive power heating pulses supplied by the DC power supply to the inductor 240. Additionally or alternatively, the controller 330 can regulate the power supply by regulating the duration (in other words, the length) of each of the successive power heating pulses supplied by the DC power supply to the inductor 240.

The controller 330 is programmed to perform a calibration process to obtain calibration values at which the conductivity is measured at known temperatures of the current collector 160. The known temperatures of the current collector may be a first calibration temperature corresponding to a first calibration value and a second calibration temperature corresponding to a second calibration value. Preferably, the calibration process is performed each time the user controls the aerosol-generating device 200, for example, each time the user inserts the aerosol-generating article 100 into the aerosol-generating device 200.

During the calibration process, the controller 330 controls the DC-AC converter 340 to continuously or continuously supply power to the inductor 240 to heat the current collector 160. The controller 330 monitors the conductivity or resistance associated with the current collector 160 by measuring the current I _DC consumed by the power supply and, optionally, the voltage V _DC of the power supply. As discussed above with respect to Fig. 6, as the current collector 160 heats up, the measured current decreases until a first critical point is reached and the current begins to increase. This first critical point corresponds to a local minimum conductivity value (local maximum resistance value). The controller 330 can record the local minimum conductivity value (or local maximum resistance) as a first calibration value. The controller can record the conductivity or resistance value at a predetermined time after reaching the minimum current as a first calibration value. The conductivity or resistance can be determined based on the measured current I _DC and the measured voltage V _DC . Alternatively, it can be assumed that the voltage V _DC of the power supply, which is a known property of the power source 310, is approximately constant. The temperature of the current collector 160 at the first calibration value is called the first calibration temperature. Preferably, the first calibration temperature is from 150 degrees Celsius to 350 degrees Celsius. More preferably, when the substrate 110 forming the aerosol contains tobacco, the first calibration temperature is 320 degrees Celsius. The first calibration temperature is at least 50 degrees Celsius lower than the second calibration temperature.

As the controller 330 continues to regulate the power supplied by the DC/AC converter 340 to the inductor 240, the measured current increases until the second critical point is reached and the maximum current is observed (according to the Curie temperature of the second current collector material) before the measured current begins to decrease. This critical point corresponds to the local maximum conductivity value (local minimum resistance value). The controller 330 records the local maximum conductivity value (or local minimum resistance value) as a second calibration value. The temperature of the current collector 160 at the second calibration value is called the second calibration temperature. Preferably, the second calibration temperature is from 200 degrees Celsius to 400 degrees Celsius. When the maximum value is detected, the controller 330 controls the DC-AC converter 340 to interrupt the power supply to the inductor 240, which results in a decrease in the temperature of the current collector 160 and a corresponding decrease in conductivity.

Due to the shape of the graph, this process of continuously heating the current collector 160 to obtain the first calibration value and the second calibration value can be repeated at least once. After interrupting the power supply to the inductor 240, the controller 330 continues to monitor the conductivity (or resistance) until a third critical point is observed, corresponding to the second minimum conductivity value (the second maximum resistance value). When the third critical point is detected, the controller 330 controls the DC-AC converter 340 to continuously supply power to the inductor 240 until a fourth critical point is detected, corresponding to the second maximum conductivity value (the second minimum resistance value). The controller 330 stores the conductivity value or the resistance value at the third critical point or immediately after it as the first calibration value and the conductivity value or the resistance value at the fourth critical current point as the second calibration value. Repeating the measurement of critical points corresponding to the minimum and maximum measured current significantly improves subsequent temperature control during user operation with the aerosol generating device. Preferably, the controller 330 regulates the power supply based on the conductivity or resistance values obtained from the second maximum and the second minimum, which is more reliable since the heat will have more time to distribute within the aerosol-forming substrate 110 and the current collector 160.

To further improve the reliability of the calibration process, the controller 310 can be additionally programmed to perform a preheating process before the calibration process. For example, if the aerosol-forming substrate 110 is particularly dry or is in similar conditions, the calibration can be performed before the heat spreads inside the aerosol-forming substrate 110, which reduces the reliability of the calibration values. If the aerosol-forming substrate 110 was wet, the susceptor 160 requires more time to reach the temperature at the minimum point (due to the water content in the substrate 110).

In order to perform the preheating process, the controller 330 is configured to continuously supply power to the inductor 240. As described above, the current begins to decrease with an increase in the temperature of the current collector 160 until a minimum is reached. At this stage, the controller 330 is configured to wait for a predetermined period of time to allow the current collector 160 to cool down before continuing to heat. Therefore, the controller 330 controls the DC-AC converter 340 to interrupt the supply of power to the inductor 240. After the predetermined period of time has elapsed, the controller 330 controls the DC-AC converter 340 to provide power until a minimum is reached. At this point, the controller controls the DC-AC converter 340 to again interrupt the supply of power to the inductor 240. The controller 330 again waits for the same predetermined period of time to allow the current collector 160 to cool down before continuing to heat. This heating and cooling of the current collector 160 is repeated during a predetermined duration of the preheating process. The predetermined duration of the preheating process is preferably 11 seconds. The predetermined total duration of the preheating process with the subsequent calibration process is preferably 20 seconds.

If the aerosol-forming substrate 110 is dry, the first minimum of the preheating process is reached within a given period of time, and the power interruption will be repeated until the end of the given period of time. If the aerosol-forming substrate 110 is wet, the first minimum of the preheating process will be reached by the end of the given period of time. Thus, performing the preheating process for a given duration ensures that, regardless of the physical state of the substrate 110, this time will be sufficient for the substrate 110 to reach the minimum temperature in order to be ready for continuous power supply and to reach the first maximum value. This allows calibration to be performed as early as possible, but still without the risk that the substrate 110 would not reach the minimum point in advance.

In addition, the aerosol generating article 100 can be designed so that the minimum is always reached within a given duration of the preheating process. If the minimum is not reached within a given duration of the preheating process, this can indicate that the aerosol generating article 100 containing the aerosol forming substrate 110 is not suitable for use with the aerosol generating device 200. For example, the aerosol generating article 100 can contain the aerosol forming substrate 110, which is different or has a lower quality than the aerosol forming substrate 100 intended for use with the aerosol generating device 200. As another example, the aerosol generating article 100 may not be configured for use with the heating device 320, for example, if the aerosol generating article 100 and the aerosol generating device 200 are manufactured by different manufacturers. Thus, the controller 330 may be configured to generate a control signal for stopping the operation of the aerosol generating device 200.

The preheating process may be performed in response to receiving a user input, such as a user activation of the aerosol generating device 200. Additionally or alternatively, the controller 330 may be configured to detect the presence of the aerosol generating article 100 in the aerosol generating device 200, and the preheating process may be performed in response to detecting the presence of the aerosol generating article 100 within the cavity 220 of the aerosol generating device 200.

Fig. 7 is a graph of conductivity versus time showing the heating profile of the current collector 160. The graph illustrates two successive heating phases: a first heating phase 710, including the preheating process 710A and the calibration process 710B described above, and a second heating phase 720, corresponding to the user's operation with the aerosol generating device 200 to generate an aerosol. Although Fig. 7 illustrates a graph of conductivity versus time, it should be understood that the controller 330 can be configured to control the heating of the current collector during the first heating phase 710 and the second heating phase 720 based on the measured resistance or current, as described above.

In addition, although the methods for controlling the heating of the current collector during the first heating phase 710 and the second heating phase 720 have been described above based on a determined conductivity value or a determined resistance value associated with the current collector, it should be understood that the methods described above can be performed based on a current value measured at the input of the DC to AC converter 340.

As can be seen from Fig. 7, the second heating phase 720 includes a plurality of conductivity stages corresponding to a plurality of temperature stages from the first operating temperature of the current collector 160 to the second operating temperature of the current collector 160. The first operating temperature of the current collector is the minimum temperature at which the aerosol-forming substrate will form an aerosol in a sufficient volume and quantity for a satisfactory sensation when inhaled by the user. The second operating temperature of the current collector is the temperature at the maximum temperature at which it is desirable to heat the aerosol-forming substrate so that the user inhales the aerosol. The first operating temperature of the current collector 160 is greater than or equal to the first calibration temperature of the current collector 160 at the minimum point of the current graph shown in Fig. 6. The first operating temperature can be from 150 degrees Celsius to 330 degrees Celsius. The second operating temperature of the current collector is less than or equal to the second calibration temperature of the current collector 160 at the Curie temperature of the second current collector material. The second operating temperature can be from 200 degrees Celsius to 400 degrees Celsius. The difference between the first operating temperature and the second operating temperature is at least 50 degrees Celsius. The first operating temperature of the current collector is the temperature at which the aerosol-forming substrate 110 forms an aerosol, so that the aerosol is formed during each temperature step.

It should be understood that the number of temperature stages illustrated in Fig. 7 is exemplary, and that the second heating phase 720 includes at least three successive temperature stages, preferably from two to fourteen temperature stages, most preferably from three to eight temperature stages. Each temperature stage may have a predetermined duration. Preferably, the duration of the first temperature stage is longer than the duration of the subsequent temperature stages. The duration of each temperature stage is preferably more than 10 seconds, preferably from 30 to 200 seconds, more preferably from 40 to 160 seconds. The duration of each temperature stage may correspond to a predetermined number of user puffs. Preferably, the first temperature stage corresponds to four user puffs, and each subsequent temperature stage corresponds to one user puff.

During the duration of each temperature step, the temperature of the current collector 160 is maintained within the target operating temperature, which corresponds to the corresponding temperature step. Thus, during the duration of each temperature step, the controller 330 regulates the power supply to the heating device 320 in such a way that the conductivity is maintained within the value, corresponding to the target operating temperature of the corresponding temperature step, as described above. The target conductivity values for each temperature step can be stored in the memory of the controller 330.

As an example, the second heating phase 720 may comprise five temperature steps: wherein the first temperature step has a duration of 160 seconds and a target conductivity value , where the second temperature step has a duration of 40 seconds and a target conductivity value , with the third temperature stage having a duration of 40 seconds and a target conductivity value , with the fourth temperature step having a duration of 40 seconds and a target conductivity value and the fifth temperature stage has a duration of 85 seconds and a target conductivity value . These temperature steps may correspond to temperatures of 330 degrees Celsius, 340 degrees Celsius, 345 degrees Celsius, 355 degrees Celsius and 380 degrees Celsius. Fig. 8 shows a block diagram of a method 800 for regulating the production of an aerosol in an aerosol generating device 200. As described above, the controller 330 may be programmed to perform the method 800.

The method begins with step 810, in which the controller 330 detects user operation with the aerosol generating device 200 to generate an aerosol. Detecting user operation with the aerosol generating device 200 may include detecting user input, such as user activation of the aerosol generating device 200. Additionally or alternatively, detecting user operation with the aerosol generating device 200 may include detecting that the aerosol generating article 100 has been inserted into the aerosol generating device 200.

In response to detecting a user operation in step 810, the controller 330 may be configured to perform the optional preheating process described above. At the end of the predetermined duration of the preheating process, the controller 330 performs a calibration process (step 820), as described above. Alternatively, the controller 330 may be configured to proceed to step 820 in response to detecting a user control in step 810. After completing the calibration process, the controller 330 performs a second heating phase, during which an aerosol is obtained in step 840.

For the purpose of the present description and the appended claims, except where otherwise indicated, all numbers expressing quantities, amounts, percentages, etc., are to be understood as modified in all instances by the term "about". Also, all ranges include the disclosed maximum and minimum points and include any intermediate ranges therebetween that may or may not be specifically listed herein. In this context, the number A may be considered to include numerical values that are within the common standard error for measuring the property that the number "A" modifies. The number A, in some instances, when used in the appended claims, may vary by the percentages listed above, provided that the amount by which A varies does not materially affect the essential and novel characteristic(s) of the claimed invention. Also, all ranges include the disclosed maximum and minimum points and include any intermediate ranges therebetween that may or may not be specifically listed herein.

Claims (32)

1. A method for regulating the production of an aerosol in an aerosol generating device, wherein the device comprises an induction heating device and a power source for supplying power to the induction heating device, and wherein the method includes: regulating the power supplied to the induction heating device to provide a stepwise increase in the temperature of a current collector associated with the aerosol generating device from a first operating temperature to a second operating temperature, wherein the current collector is configured to heat the aerosol forming substrate, and wherein the power is regulated based on the measured resistance, conductivity or current associated with the current collector, and wherein the measured resistance, conductivity or current associated with the current collector is determined based on a direct current drawn from the power source. 2. The method according to paragraph 1, characterized in that the step-by-step increase in the temperature of the current collector includes at least three successive temperature steps, wherein each temperature step has a certain duration. 3. The method according to claim 2, characterized in that the duration is at least 10 seconds. 4. The method according to paragraph 2, characterized in that the duration corresponds to a specified number of puffs by the user. 5. The method according to any of paragraphs 1-4, characterized in that the first temperature stage has a longer duration than the subsequent temperature stages. 6. The method according to any one of paragraphs 1-5, characterized in that the first working temperature is sufficient for the formation of an aerosol by the aerosol-forming substrate. 7. The method according to any one of paragraphs 1-6, characterized in that the current collector and the aerosol-forming substrate form part of an aerosol-generating article, and the aerosol-generating device is designed with the possibility of placing the aerosol-generating article in a removably positionable manner. 8. The method according to any one of paragraphs 1-7, characterized in that it further includes performing a calibration process for measuring one or more calibration values associated with the current collector. 9. The method according to claim 8, characterized in that the regulation of the power supplied to the induction heating device includes regulation of the power supply in such a way that the temperature of the current collector is regulated on the basis of one or more calibration values. 10. The method according to claim 8 or 9, characterized in that one or more calibration values comprise a first conductivity value associated with a first calibration temperature of the current collector, and a second conductivity value associated with a second calibration temperature of the current collector, or wherein one or more calibration values comprise a first resistance value associated with a first calibration temperature of the current collector and a second resistance value associated with a second calibration temperature of the current collector. 11. The method according to claim 10, characterized in that the current collector comprises a first current collector material having a first Curie temperature and a second current collector material having a second Curie temperature, wherein the second Curie temperature is lower than the first Curie temperature, and wherein the second calibration temperature corresponds to the second Curie temperature of the second current collector material. 12. The method according to claim 10 or 11, characterized in that the regulation of the power supplied to the induction heating device includes regulation of the power supply in such a way that the temperature of the current collector is between the first calibration temperature and the second calibration temperature. 13. The method according to any one of paragraphs 8-12, characterized in that the calibration process is performed during the user's operation with the aerosol-generating device to obtain the aerosol. 14. The method according to any one of paragraphs 10-13, characterized in that it additionally includes performing a preheating process to heat the current collector to a first calibration temperature, wherein the preheating process has a specified duration. 15. An aerosol generating device comprising: a power source for supplying a DC supply voltage and a DC current; an electronic power supply circuit connected to the power source, wherein the electronic power supply circuit comprises: DC to AC converter; an inductor connected to a DC to AC converter for generating an alternating magnetic field when excited by alternating current from the DC to AC converter, wherein the inductor is configured to be connected to a current collector, wherein the current collector is configured to heat the substrate forming the aerosol; and a controller configured to regulate power supplied to the electronic circuit of the power supply unit to cause a stepwise increase in the temperature of the current collector from a first operating temperature to a second operating temperature, and wherein the power is regulated based on the measured resistance, conductivity or current associated with the current collector, wherein the measured resistance, conductivity or current associated with the current collector is determined based on the direct current consumed from the power source. 16. An aerosol generating device according to claim 15, characterized in that the stepwise increase in the temperature of the current collector includes at least three successive temperature steps, wherein each temperature step has a certain duration, and during the duration of each temperature step the controller is configured to regulate the power supplied to the electronic circuit of the power supply unit in order to maintain the temperature of the current collector at a given temperature. 17. An aerosol generating device according to claim 16, characterized in that the duration is specified. 18. An aerosol generating device according to any one of paragraphs 15-17, characterized in that it further comprises: a current sensor configured to measure, on the input side of the DC to AC converter, the DC current consumed from the power source, wherein the conductivity value and the resistance value associated with the current collector are determined based on the DC supply voltage of the power source and based on the DC current consumed from the power source. 19. An aerosol generating device according to claim 18, characterized in that it additionally contains a voltage sensor configured to measure, on the input side of the DC to AC converter, the voltage of the DC power supply of the power source. 20. An aerosol generating device according to any one of paragraphs 15-19, characterized in that the controller is further configured to perform a calibration process for measuring one or more calibration values associated with the current collector. 21. The aerosol generating device of claim 20, wherein the one or more calibration values comprise a first conductivity value associated with a first calibration temperature of the current collector and a second conductivity value associated with a second calibration temperature of the current collector, or wherein one or more calibration values comprise a first resistance value associated with a first calibration temperature of the current collector and a second resistance value associated with a second calibration temperature of the current collector. 22. An aerosol generating device according to any one of paragraphs 15-21, characterized in that the first operating temperature is from 150 degrees Celsius to 330 degrees Celsius, and the second operating temperature is from 200 degrees Celsius to 400 degrees Celsius, wherein the temperature difference between the first operating temperature and the second operating temperature is at least 30 degrees Celsius. 23. An aerosol generating system comprising an aerosol generating device according to any one of paragraphs 15-22 and an aerosol generating article, wherein the aerosol generating article comprises an aerosol generating substrate and a current collector. 24. The aerosol generating system of claim 23, wherein the current collector comprises a first current collecting material and a second current collecting material, wherein the first current collecting material is located in physical contact with the second current collecting material, wherein the first current-receiving material has a first Curie temperature, and the second current-receiving material has a second Curie temperature, wherein the second Curie temperature is lower than the first Curie temperature. 25. An aerosol generating system according to claim 24, characterized in that the second calibration temperature corresponds to the Curie temperature of the second current-collecting material.